The three were detained for taking part in political protests, all while under the age of 18. The charity claims they were “tortured into false ‘confessions.’”

“Theresa May’s bid to be the Gulf’s ‘partner of choice’ sounds more like a sales pitch than a much-needed call for reform,” Reprieve director Maya Foa said in a statement.

“Despite years of substantial UK support apparently intended to improve the human rights situation in the Gulf, Bahrain and Saudi Arabia continue to torture and sentence to death juveniles and political dissidents – an appalling breach of the ‘international norms’ that Mrs May says she wants to promote.

“If the prime minister is going to commit the UK to greater cooperation with the Gulf, she must also call for an immediate end to these abuses – and the release of prisoners like Ali al-Nimr,” Foa added.

Ahead of her three-day visit, May told the BBC: “No doubt there will be some people in the UK who say we shouldn’t seek stronger trade and security ties with these countries because of their record on human rights.”

She argued that better human rights records could only be achieved “by stepping up, engaging with these countries and working with them to encourage and support their plans for reform.

“That is how Britain can be a force for good in the world as well as helping to keep our people safe and create new opportunities for business.”